QSARs for Predicting Cation Toxicity, Bioconcentration, Biosorption, and Binding - Fundamental QSARs for Metal Ions - page 219

the logarithm of the first hydrolysis constant (|log K OH |), and the ionic index Z 2 /r)
( Table 5.4 ) . The log K QSARs for the water flea ( Daphnia magna ) were developed
from 14 studies with 7 cations. The log K QSARs for Daphnia magna that used σ p
had the highest r 2 value and the lowest p value (Table 5.22). The log K QSARs for
the fathead minnow ( Pimephales promelas ) were developed from 11 studies with
7 cations. The log K QSARs for Pimephales promelas that used σ p also had the
highest r 2 value and the lowest p value, even though the 7 cations for Pimephales
promelas were different from those used for Daphnia magna (Table 5.22). The
log K -based QSARs for the rainbow trout ( Oncorhynchus mykiss ) were developed
from 14 studies with 7 cations. The log K -based QSARs for Oncorhynchus mykiss
that used σ p also had the highest r 2 value and the lowest p value (Table 5.22). The
QSARs for barley ( Hordeum vulgare ) were developed from 6 studies with 6 cations.
The log K -based QSARs for Hordeum vulgare that used |log K OH | had the highest
r 2 value and the lowest p value (Table 5.22). Similar QSARs for the earthworm
( Eisenia fetida ) were developed from 6 studies with 6 cations. The log K QSARs
for the Eisenia fetida that used |log K OH | had the highest r 2 value and the lowest p
value (Table 5.22).

TABLE 5.22
Zhou et al. (2011) Binding Constant QCARs
Species Cations QCAR r 2 p

Water flea
( Daphnia
magna )

Ag 1+ , Ca 2+ , Cd 2+ , Cu 2+ , Mg 2+ ,
Na 1+ , Zn 2+

Log K = 11.69 − 43.9σ p
Log K = 2.36 + 1.71 X r

0.89
0.73
0.41
0

0.0001
0.0001
0.01
0.96

2
Log K = 13.99 − 0.72 Log K OH
Log K = 5.88 − 0.11 Z 2 /r

Fathead Minnow
( Pimephales
promelas )

Ag 1+ , Ca 2+ , Cd 2+ , Cu 2+ , Na 1+ ,
Ni 2+ , Zn 2+

Log K = 10.57 − 37.62σ p
Log K = 2.18 + 1.54 X r
m

084
0.66
0.53
0.09

0.0001
0.002
0.01
0.37

2
Log K = 12.6 − 0.66 Log K OH
Log K = 3.96 + 0.33 Z 2 /r

Rainbow Trout
( Oncorhynchus
mykiss )

Ca 2+ , Cd 2+ , Co 2+ , Cu 2+ , Mg 2+ ,
Pb 2+ , Zn 2+

Log K = 11.08 − 42.73 σ p
Log K = 3.9 + 0.69 X r

0.82
0.40
0.41
0.02

0.0001
0.04
0.01
0.57

2
Log K = 10.2 − 0.49 Log K OH
Log K = 3.69 + 0.37 Z 2 /r

Barley ( Hordeum
vulgare )

Ca 2+ , Co 2+ , Cu 2+ , K 1+ , Mg 2+ ,
Ni 2+ ,

0.61
0.60
0.74
0.33

0.06
0.07
002
0.29

2
Log K = 9.41 − 34.59 σ p
Log K = 12.44 − 0.76 Log K OH
Log K = 1.52 + 0.55 Z 2 /r

Log K = 0.51 + 1.91 X r
m

Earthworm
( Eisenia fetida )

Ca 2+ , Cd 2+ , Co 2+ , Cu 2+ , Mg 2+ ,
Ni 2+ ,

0.60
0.35
0.82
0.21

0.07
0.22
0.01
0.35

Log K = 0.82 + 1.68 X r

2
Log K = 7.78 − 25.36 σ p
Log K = 11.61 − 0.68 Log K OH
Log K = 1.35 + 0.63 Z 2 /r

Source: Data from D.M. Zhou, L.Z. Li, W.J.G.M. Peijnenburg, D.R. Ownby, A.J. Hendriks, P. Wang, and
D.D. Li, “A QICAR Approach for Quantifying Binding Constants for Metal-Ligand Complexes.”
Ecotox. Environ. Safety 74 (2011):1036-1042.